Explained: What is leap second? Why are we scrapping it?
Meta and Google are among the tech companies that have demanded for leap seconds to be ditched. CGPM has decided to scrap the practice from 2035.
The world’s top metrology body has decided to end the practice of adding ‘leap seconds’ to official clocks to keep them in sync with Earth’s rotation from 2035. The decision was taken in a meeting of global representatives at the General Conference on Weights and Measures (CGPM) in Paris on Friday, Nature reported.
What is leap second?
In the time standard which we follow, the Coordinated Universal Time, or UTC, a day lasts 86,400 seconds (24 hours * 60 minutes * 60 seconds). A second on UTC - which becomes the reference for international time zones- is calculated by averaging signals from around 400 atomic clocks. These clocks are so accurate that they lose only about a second in 1,400,000 years.
However, the average length of a day is not always 24 hours, but depends on how long it takes for the Earth to rotate around the Sun - solar time. According to Nasa, it takes about 86,400.002 seconds long. So leap seconds are added to stop UTC going out of sync from solar time at a rate of about one minute every 90 years. A leap second is normally inserted either on June 30 or December 31.
Why was there a demand to stop this practice?
There were primarily three reasons given in support to abolish the synchronization practice.
1) Earth’s orbit is not precisely predictable. Nasa states the length of day is affected by many factors, primarily by the atmosphere over periods less than a year, thus the change can not be pre-programmed.
In addition, we have recently seen unusual sped-up in the Earth’s rotation.
2) Experts say there is no convincing data that anything major would crop up if we don’t add leap second.
3) Tech companies have to synchronise their digital systems around the world. But as the leap year is typically announced only six months in advance by the International Earth Rotation and Reference Systems Service in Frankfurt, Germany, they cannot be pre-programmed into software.
However, a major mishap can happen if the seconds get enforced inconsistently in different systems, clocks can temporarily go out of sync, probably bringing snags that can stop computers and leave international financial markets exposed to attack.
Meta and Google are among the tech companies that had demanded for leap seconds to be ditched.